Impregnating corrugated cardboard

ABSTRACT

An apparatus for impregnating corrugated cardboard with a waterproofing or protective material is described. The corrugated board including a plurality of laterally extending open ended flutes is fed between an impregnant supply means and a suction means. The impregnant supply means includes a nozzle means for injecting a concentrated jet of impregnating material a substantial distance into said laterally extending flutes. The cross-sectional area of the concentrated jet is smaller than the cross-sectional area of said flutes in the provision of a gaseous medium surrounding said jet at the entrance of said flutes. The suction means creates a vacuum which draws the impregnating material of said jet and the surrounding gaseous medium through said flutes. Means are provided for adjusting the position of said nozzle means with respect to said corrugated board and the quantity of impregnating material supplied to said flutes. Means are further provided for sensing the presence or absence of the corrugated board in area of said nozzles and for cutting the impregnant supply means on or off in response thereto.

4 United States Patent [191 Lau et al.

[ July 29, 1975 IMPREGNATING CORRUGATED CARDBOARD [76] Inventors: Giinther Lau, Glogauerstr. 22, 8541 Katzwang; Edmund Bradatsch, l-luttenwerkstr. 5, 8481 Weiherhammer; Hermann J. Brandl, Virchowstr. 33, 85 Nurnberg; Georg Niggel, Rothenbachstr. 11, 8481 Weiherhammer, all of Germany 22 Filed: Jan. 8, 1973 211 Appl. No.: 321,840

[30] Foreign Application Priority Data Jan. 14, 1972 Germany 2201744 [52] US. Cl. 118/50; 118/317 [51] Int. Cl. B05C 7/02 [58] Field of Search 118/2, 314, 50, 317, 8; 134/152, 171; 15/306, 308

[56] References Cited UNITED STATES PATENTS 1,592,824 7/1926 Fairchild 118/317 X 3,043,014 7/1962 Loechl 118/2 X 3,348,519 10/1967 Dyess, Jr. et al. 118/2 3,669,064 6/1972 Hoelzinger et a1 118/50 X 3,669,067 6/1972 Achermann et al. 118/50 Primary ExaminerJohn P. McIntosh Attorney, Agent, or Firm- -Silverman & Cass, Ltd.

[ 5 7] ABSTRACT An apparatus for impregnating corrugated cardboard with a waterproofing or protective material is described. The corrugated board including a plurality of laterally extending open ended flutes is fed between an impregnant supply means and a suction means. The impregnant supply means includes a nozzle means for injecting a concentrated jet of impregnating material a substantial distance into said laterally extending flutes. The cross-sectional area of the concentrated jet is smaller than the cross-sectional area of said flutes in the provision of a gaseous medium surrounding said jet at the entrance of said flutes. The suction means creates a vacuum which draws the impregnating material of said jet and the surrounding gaseous medium through said flutes. Means are provided for adjusting the position of said nozzle means with respect to said corrugated board and the quantity of impregnating material supplied to said flutes. Means are further provided for sensing the presence or absence of the corrugated board in area of said nozzles and for cutting the impregnant supply means on or off in response thereto.

3 Claims, 10 Drawing Figures P'ATENTEU JUL29 m5 3. 8 96.; 76 3 SHEET 3 Fig. 3

Fig. 4

PATENTEnJuLzems 3.896.763

SHEET Fig. 7

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PATENTEI] JUL2 91975 SHEET 1 IMPREGNATING CORRUGATED CARDBOARD BACKGROUND OF INVENTION Statement of Invention The present invention relates to an apparatus for impregnating rapidly moving corrugated board, having a succession of transversely extending open ended longitudinal flutes therein, wherein the impregnating material is injected into a first end of said flutes, under pressure, in the form of a concentrated jet of impregnating material having a cross sectional area less than the cross sectional area of the flutes into which it is injected, while a suction means is disposed adjacent the opposite ends of the respective flutes for drawing said impregnating material in said jet and any surrounding gaseous medium through said open ended flutes to thereby impregnate the interior of the corrugated board.

Description of Prior Art In an impregnating apparatus for corrugated cardboard where the impregnating agent is inserted into the interior of the corrugated board and where impregnation is thus accomplished from the inside toward the outside, it is known that the impregnating agent can be supplied, under pressure, to the moving horizontally lying corrugated cardboard along an open longitudinal edge and that the interior of the corrugated cardboard can be exposed to a suction action from the other longitudinal edge. In these known apparatus several spray nozzles are provided and the impregnating agent is fed to these nozzles under pressure. These nozzles inject the impregnating agent into the interior of the corrugated paper in the form of an atomized spray. The flow of the impregnating agent laterally to the direction of movement of the corrugated paperboard in the interior of the same is facilitated in the prior art by the combined action of the spraying of the impregnating agent, which completely fills the existing lateral ducts or flutes on the application side, and the suction of the sprayed material through said ducts or flutes. This known apparatus entails the disadvantage that, in practice, the necessary machine length becomes quite long if one wishes to achieve the desired application. volume in a reproducible manner. Moreover, it is difficult in these known apparatus to vary the application volume. Apparatus of this type are disclosed in US. Pat. No. 3,669,064 to Hoelzinger et al. and US. Pat. No. 3,669,067 to Achermann et al., both of which are assigned to the same assignee as the present invention.

The above mentioned prior art methods further suffer from the disadvantage that the production speeds attainable are not as fast as that of the present invention.

PURPOSE OF THE INVENTION Accordingly, it is an object of the present invention to provide an apparatus for impregnating corrugated board having a high production speed for use in an inline process for producing saidcorrugated board.

It is another object of the present invention to provide an apparatus for impregnating corrugated board, which offers a variable but uniform weight application of the impregnating material.

It is still another object of the present invention to provide an apparatus for impregnating corrugated board which facilitates good reproducibility of the quantities of impregnating materials applied.

It is a further object of the present invention to provide an apparatus for impregnating corrugated board which enables the board fabricating machine to be of a minimum length.

SUMMARY OF THE INVENTION These and other objects of the present invention are accomplished by injecting a concentrated jet of impregnating material, which is substantially free of air, into a first end of the flutes'or ducts of a corrugated board, the cross section of the concentrated jet being less than the cross section of the associated flutes in the provision of gaseous medium, such as air, in the area surrounding the concentrated jet at the entrance of said flutes, and drawing said concentrated jet and impregnating material through said flutes from the opposite side of said corrugated board by a suitable suction means. The impregnating material may be selected from the group consisting of plastics, water glass, bitumen, parafin, resin, glue, paraffin-bitumenized emulsion, artificial resin wax mixture, liquid synthetic materials, foaming plastics, artificial resins, silicon, sodium silicate solution, alkali metal silicate, vinyl resin, and any other material which would occur to one of ordinary skill in the art to provide durability and waterproofing to corrugated cardboard.

The apparatus of the present invention facilitates the penetration of the concentrated jet of impregnating material a substantial distance into the flutes or ducts in a direction transverse to the movement of said corrugated board. This causes a considerable amount of the flutes or ducts to be impregnated, even before the suction action from the opposite sides of said flutes enhances or continues the flow of the impregnating material through the flutes of said corrugated cardboard. The presence of a gaseous medium surrounding the concentrated jet of impregnating material provides a high pressure differential between the side of said flutes in which the impregnating material is injected and the vacuum created in the suction means at the opposite end of the flutes. This pressure differential causes the gaseous medium surrounding the jet at the entrance end of said flutes to be drawn through the flutes at a rapid rate, wherein the movement of the gaseous medium helps carry the impregnating material of the jets the remainder of the distance through said flutes.

The apparatus of the present invention permits a very uniform weight application of the impregnating material coupled with maximum production speed. Furthermore, good variability of application coupled with good reproducibility are obtained. Finally, minimum machine length because of the fast feed rate of the impregnating material laterally through the corrugated board is facilitated.

According to one version of the invention, the injection jet has the shape of a full jet, a flat jet, or a broadslit jet. If the broad-slit jet is used it is possible to further shorten the structural length of the machine, because now fewer nozzles are needed next to each other in the direction of movement of the corrugated paper course.

In a preferred embodiment the device for implementing the method according to the invention, with at least one nozzle associated with the one open longitudinal edge of the corrugated board for the injection of the concentrated jet of impregnating agent into the corrugated board, the nozzle is placed as closely as possible to the longitudinal edge of the corrugated board to permit the jet to penetrate as deeply as possible into the board before the suction means draws the material the remainder of the distance.

In order to facilitate the adjustment of the nozzle openings toward the corrugated board, the height of the nozzle can be adjusted, according to another feature of the invention, that is, it can be swung around an axis parallel to the direction of movement of the corrugated board. Furthermore, the nozzle can be adjusted with respect to the longitudinal edge of the corrugated board.

BRIEF DESCRIPTION OF DRAWINGS Other objects and attendant advantages of the present invention will become more fully apparent with reference to the following description of the accompanying drawings wherein:

FIG. 1 illustrates a schematic vertical cross-section through the apparatus for impregnating a corrugated board according to the present invention;

FIG. 2 is a top plan view of the apparatus of FIG. 1;

FIG. 3 is a schematic vertical cross-section through a first embodiment of an injection nozzle of the present invention;

FIG. 4 is a top view of the nozzle of FIG. 3;

FIG. 5 is a vertical cross-section of a second embodiment of an injection nozzle for use with the present invention;

FIG. 6 is a top view of the nozzle of FIG. 5;

FIG. 7 is a vertical cross-section of a third embodiment of an injection nozzle for use with the present invention;

FIG. 8 is a top view of the nozzle of FIG. 7;

FIG. 9 is a top plan view of the apparatus according to the invention illustrating control means for turning the nozzles on or off;

FIG. 10 is a schematic vertical cross-section of the apparatus of FIG. 9.

DESCRIPTION OF SPECIFIC EMBODIMENTS The device for impregnating a corrugated board as illustrated in FIGS. 1 and 2 consists of an application device generally designated 1 and a suction means 2 disposed on opposite sides of a corrugated board 3, which is to be impregnated with an impregnating material. Preferably, the impregnating device is inserted inline into an installation for the production of the corrugated board, where the corrugated boards to be produced are moved along a horizontal plane at a rapid rate past the impregnating device. Along longitudinal edges 4 and 5 of corrugated board 3, the corrugated board is supported by longitudinal guides 6 and 7. The longitudinal guide 6 consists of a fixed lower angular guide rail 8 and an upper, angular guide rail 9, which can be adjusted vertically and which can be fixed in position. The guide parts 10 and 11 of the longitudinal edge guide 7 can be integral with suction means 2.

The application device 1 includes at least one nozzle 12, a distributor means 13, and a control unit 14. The impregnating material, which is pressurized by a pump (not shown) is moved, via pipeline 14, to the control unit 14 and from there via the distributor means 13 on to the nozzle 12. The control unit 14 can be operated pneumatically or electromagnetically. A suitable switchable routing valve (not shown) of the control unit 14, in one switching position, facilitates the free passage of the impregnating material to the nozzles 12, while the second switching position connects the feed line 15 with a return line for the impregnating agent, so that, even after the nozzles are shut off, the impregnating material can be recirculated to avoid stoppages or the like. By means of control unit 14, we can control two nozzles 12 due to the use of the distributor means 13. As can be-seen from FIG. 2, a large number of nozzle control units 12, 13, and 15, next to each other, may be provided.

To make sure that the impregnating material jet, which comes out of nozzle 12, penetrates a sufficient distance into the interior of the corrugated flutes or ducts in the corrugated board 3, the carrier 16 of the nozzle control unit 12, 13, 14 can be adjusted vertically in the direction of arrow I. It can also be adjusted horizontally in the direction of arrow II, and it can be swung around an axis parallel to the longitudinal edge of corrugated board 3 in the direction of arrow III.

As illustrated in FIGS. 3 and 4, nozzle 2 has the form of a flat-jet nozzle which generates a sharp, fan-shaped jet. For this purpose, the nozzle bore-hole 17 turns into a nozzle exit opening 18 whose cross-section, in the horizontal plane, has the shape of a circular segment while it is triangular in the vertical plane. As will become more fully apparent hereinafter with reference to FIGS. 5 to 8, other forms can be used for the nozzle outlet opening 18. The essential thing is that the nozzle outlet opening 18 should guide the impregnating agent jet 19 as completely as possible into the interior 20 of the corrugated board, whereby the jet can be fanned out more or less, parallel to the corrugated horizontal plane. The cross-sectional area of jet 19 allows the entry of a gaseous medium in the arrow direction indicated in FIG. 3 into the corrugated board in the area surrounding jet 19. This presupposes that the nozzle opening 18 is at a short distance from longitudinal edge 4 of the corrugated board 3. On the other hand, the nozzle opening 18 should be placed as closely as possible to the longitudinal edge 4 of the corrugated board 3 because otherwise there is a danger that an essential portion of the impregnating material jet 19 will not penetrate a sufficient distance into the interior 20 of the corrugated board.

In order to draw the air or gaseous medium into the interior 20 of the corrugated board 3, the opposite edge of the corrugated board is connected to a suction means 2 which includes a vacuum pump with a prepositioned impregnating material cutter, not shown. The corrugated board interior 20 is, as usual, subdivided into ducts or flutes which are separated from each other and which run laterally to the direction of movement of the corrugated board. The inside wall of these canals is impregnated by means of the impregnating agent. The impregnating agent is impregnated over a substantial distance from the longitudinal edge 4 by the penetration of the impregnating material jet 19. The impregnating material, which comes out of the nozzle exit opening 18 under high pressure is eventually reduced to very fine droplets toward the end of its path of injection. These droplets gradually cling to the wall of the lateral corrugated flutes. The air or gaseous medium which is drawn through the corrugated board facilitates the further transport toward the longitudinal edge 5 of the impregnating material in jet 19. This air or gaseous medium acts as a carrier for the impregnating material as it is drawn through the interior of the board. Surplus impregnating substance is swept along into the suction means 2 and there it is separated by a cutter (not shown) and is recirculated to the impregnating agent pump or to a container connected to that pump. The air or gaseous material is blown out via the cutter from the vacuum pump, preferably a liquid seal pump.

To facilitate the adaption of the nozzle to the type of impregnating material, the nozzle mouthpiece, with nozzle duct 17 and nozzle exit opening 18 is exchangeable as we can see from FIGS. 5-8.

Referring to FIGS. 5 and 6 there is illustrated a second embodiment of the nozzle 18 of the present invention which generates a broad-slit jet. As illustrated in FIGS. 5 and 6 the nozzle has a rectangular crosssection in the vertical plane and a circular cross-section in the horizontal plane.

Referring to FIGS. 7 and 8 there is illustrated a third embodiment of the nozzle of the present invention for generating a full-jet. Nozzle 18 in the embodiment of FIGS. 7 and 8 has a triangular cross-section in the vertical plane and a linear cross-section in the horizontal plane. It should be understood that other nozzle configurations may be used without departing from the spirit and scope of this invention.

The present invention also offers the advantage that the pressure of the impregnating material pump can be changed, by virtue of the fact that the valve opening can be reduced or that the nozzle opening can be changed by means of a closing needle which can be screwed into the bore of nozzle 18 to adjust the crosssection of the nozzle opening to facilitate the adjusting of the quantity of the impregnating material injected into the corrugated board, In practice the quantity of impregnating material injected would be adjusted according to the relative speed of the corrugated board. The pressure of the impregnating material pump could also be changed as a function of the speed of the board. If the corrugated board speed goes up, it is necessary, in order to keep the impregnating material application constant in the interior of the corrugated paper course, to increase the quantity of the injected impregnating material and thus also the pressure of the impregnating material pump or by adjusting the dosing needle as a function of the speed of the corrugated board.

Adjustments of the quantity of impregnating material may be accomplished continually or phase-by-phase. If a large number of nozzles are provided, which are arranged as closely as possible in juxtaposition and can be controlled as described above, then a situation might occur where it may be desirable to adjust the nozzles in any desired sequence. As the movement speed of the board increases, nozzles which were shut off could be turned on, whereas they could be selectively shut off as the speed of movement of the board decreases.

Furthermore, it would be possible to control and/or regulate the impregnating material application by changing the temperature of the impregnating agent or the air volume flow through the corrugated flutes. Furthermore it would also be possible to influence the speed of movement of the board.

To make sure that the nozzles cannot be turned on when there is no corrugated board in the impregnating apparatus and to make sure that the latter will not be fully injected in an undesirable manner here, one or more sensors may be provided which respond to the presence of the corrugated board. Here it is a good idea to provide one sensor at the inlet and at the outlet to facilitate the actuation of the nozzles only when both sensors have been activated by the corrugated board which has come in. This may be accomplished by connecting both sensors to a conventional AND gate in suitable logic circuitry. At the end of the corrugated board the impregnating apparatus is turned off, as soon as the inlet sensor is no longer activated by the passing corrugated board. The last piece of the corrugated board of course is then no longer impregnated but we can reliably prevent the apparatus from being sprayed full.

As illustrated in FIGS. 9 and 10, the sensors 21 can be combined with nozzles 12 for the passing corrugated board 3, whereby the pertinent control units successively turn on or successively turn off the individual nozzles, controlled by the incoming or outgoing corrugated board 3.

The sensors for the presence or absence of the corrugated board 3 can also sense the position of the corrugated board and control the position of the corrugated board edge in the guides. Position sensors can additionally be provided on the suction side, preferably at the inlet and the outlet.

Any suitable type of sensors may be used. For example sensors 21 may be microswitches or light and photocell means, which can detect the presence or absence of objects as is well known in the art.

The air or gaseous medium, which is sucked in on the suction side via the corrugated flutes is preferably preheated, for which purpose it is conducted on the suction side via a heat exchanger, not shown.

If desired, air can also be forced via the heat exchanger through a blower into the corrugated paper canals. This makes it possible to preheat apparatus parts, such as, for example, the nozzles and the like, which have become cold, while starting the apparatus.

While in accordance with the provisions of the Patent Statutes the preferred form and embodiments of the invention have been illustrated and described, it will be apparent that various modifications and changes may be made without deviating from the inventive concept.

We claim:

1. Apparatus for impregnating corrugated board including a serpentine fibrous intermediate layer, and a top and bottom planar fibrous outer layer having a predetermined height therebetween and cooperating with the serpentine layer to define a succession of transversely extending open-ended flutes having said predetermined height, comprising a. means for longitudinally feeding said board with said flutes and said planar outer layers being arranged horizontally and with said flutes extending normal to the longitudinal direction of feed;

b. stationary impregnant supply means arranged adjacent one longitudinal edge of said longitudinally travelling board for supplying to one end of the flutes adjacent thereto an impregnating material, said impregnant supply means including 1. nozzle means for injecting a concentrated jet of said impregnating material, substantially devoid of air into said flutes, said concentrated jet having a height less than said predetermined height of said flutes, between said top and bottom layers 2. said nozzle means being provided with a bore hole and an exit aperture having a cross-section taken in a vertical plane through the bore hole which is substantially triangular when viewed perpendicular to the cross section, and a crosssection taken in a horizontal plane through the bore hole which is substantially semicircular when viewed perpendicular to the cross section;

0. said nozzle means and longitudinally feeding means being positioned such that said one longitudinal edge is positioned away from said nozzle means for allowing a gaseous medium entry to the flutes adjacent said nozzle means and concentrated jet as said concentrated jet is injected into said flutes for sheathing said jet as it enters said flutes, and

d. stationary suction means disposed adjacent the other longitudinal edge of said board opposite said impregnant supply means for establishing a vacuum in said flutes to draw the impregnating material in said jet and said surrounding gaseous medium therethrough.

2. Apparatus for impregnating corrugated board including a serpentine fibrous intermediate layer, and a top and bottom planar fibrous outer layer having a predetermined height therebetween and cooperating with the serpentine layer to define a succession of transversely extending open-ended flutes having said predetermined height, comprising a. means for longitudinally feeding said board with said flutes and said planar outer layers being arranged horizontally and with said flutes extending normal to the longitudinal direction of feed;

b. stationary impregnant supply means arranged adjacent one longitudinal edge of said longitudinally travelling board for supplying to one end of the flutes adjacent thereto an impregnating material, said impregnant supply means including 1. nozzle means for injecting a concentrated jet of said impregnating material, substantially devoid of air into said flutes, said concentrated jet having a height less than said predetermined height of said flutes, between said top and bottom layers 2. said nozzle means being provided with a bore hole and an exit aperture having a cross-section taken in a vertical plane through the bore hole which is substantially rectangular when viewed perpendicular to the cross section, and a crosssection taken in a horizontal plane through the bore hole which is substantially semicircular when viewed perpendicular to the cross section;

0. said nozzle means and longitudinally feeding means being positioned such that said one longitudinal edge is positioned away from said nozzle means for allowing a gaseous medium entry to the flutes adjacent said nozzle means and concentrated jet as said concentrated jet is injected into said flutes for sheathing said jet as it enters said flutes, and

d. stationary suction means disposed adjacent the other longitudinal edge of said board opposite said impregnant supply means for establishing a vacuum in said flutes to draw the impregnating material in said jet and said surrounding gaseous medium therethrough.

3. Apparatus for impregnating corrugated board including a serpentine fibrous intermediate layer, and a top and bottom planar fibrous outer layer having a predetermined height therebetween and cooperating with the serpentine layer to define a succession of transversely extending open-ended flutes having said predetermined height, comprising a. means for longitudinally feeding said board with said flutes and said planar outer layers being arranged horizontally and with said flutes extending normal to the longitudinal direction of feed;

b. stationary impregnant supply means arranged adjacent one longitudinal edge of said longitudinally travelling board for supplying to one end of the flutes adjacent thereto an impregnating material, said impregnant supply means including 1. nozzle means for injecting a concentrated jet of said impregnating material, substantially devoid of air into said flutes, said concentrated jet having a height less than said predetermined height of said flutes, between said top and bottom layers 2. said nozzle means being provided with a bore hole and an exit aperture having a cross-section taken in a vertical plane through the bore hole which is substantially triangular when viewed perpendicular to the cross-section, and a crosssection taken in a horizontal plane through the bore hole which is substantially linear when viewed perpendicular to the cross section;

c. said nozzle means and longitudinally feeding means being positioned such that said one longitudinal edge is positioned away from said nozzle means for allowing a gaseous medium entry to the flutes adjacent said nozzle means and concentrated jet as said concentrated jet is injected into said flutes for sheathing said jet as it enters said flutes, and

d. stationary suction means disposed adjacent the other longitudinal edge of said board opposite said impregnant supply means for establishing a vacuum in said flutes to draw the impregnating material in said jet and said surrounding gaseous medium therethrough. 

1. Apparatus for impregnating corrugated board including a serpentine fibrous intermediate layer, and a top and bottom planar fibrous outer layer having a predetermined height therebetween and cooperating with the serpentine layer to define a succession of transversely extending open-ended flutes having said predetermined height, comprising a. means for longitudinally feeding said board with said flutes and said planar outer layers being arranged horizontally and with said flutes extending normal to the longitudinal direction of feed; b. stationary impregnant supply means arranged adjacent one longitudinal edge of said longitudinally travelling board for supplying to one end of the flutes adjacent thereto an impregnating material, said impregnant supply means including
 1. nozzle means for injecting a concentrated jet of said impregnating material, substantially devoid of air into said flutes, said concentrated jet having a height less than said predetermined height of said flutes, between said top and bottom layers
 2. said nozzle means being provided with a bore hole and an exit aperture having a cross-section taken in a vertical plane through the bore hole which is substantially triangular when viewed perpendicular to the cross section, and a cross-section taken in a horizontal plane through the bore hole which is substantially semicircular when viewed perpendicular to the cross section; c. said nozzle means and longitudinally feeding means being positioned such that said one longitudinal edge is positioned away from said nozzle means for allowing a gaseous medium entry to the flutes adjacent said nozzle means and concentrated jet as said concentrated jet is injected into said flutes for sheathing said jet as it enters said flutes, and d. stationary suction means disposed adjacent the other longitudinal edge of said board opposite said impregnant supply means for establishing a vacuum in said flutes to draw the impregnating material in said jet and said surrounding gaseous medium therethrough.
 2. said nozzle means being provided with a bore hole and an exit aperture having a cross-section taken in a vertical plane through the bore hole which is substantially triangular when viewed perpendicular to the cross-section, and a cross-section taken in a horizontal plane through the bore hole which is substantially linear when viewed perpendicular to the cross section; c. said nozzle means and longitudinally feeding means being positioned such that said one longitudinal edge is positioned away from said nozzle means for allowing a gaseous medium entry to the flutes adjacent said nozzle means and concentrated jet as said concentrated jet is injected into said flutes for sheathing said jet as it enters said flutes, and d. stationary suction means disposed adjacent the other longitudinal edge of said board opposite said impregnant supply means for establishing a vacuum in said flutes to draw the impregnating material in said jet and said surrounding gaseous medium therethrough.
 2. said nozzle means being provided with a bore hole and an exit aperture having a cross-section taken in a vertical plane through the bore hole which is substantially rectangular when viewed perpendicular to the cross section, and a cross-section taken in a horizontal plane through the bore hole which is substantially semicircular when viewed perpendicular to the cross section; c. said nozzle means and longitudinally feeding means being positioned such that said one longitudinal edge is positioned away from said nozzle means for allowing a gaseous medium entry to the flutes adjacent said nozzle means and concentrated jet as said concentrated jet is injected into said flutes for sheathing said jet as it enters said flutes, and d. stationary suction means disposed adjacent the other longitudinal edge of said board opposite said impregnant supply means for establishing a vacuum in said flutes to draw the impregnating material in said jet and said surrounding gaseous medium therethrough.
 2. Apparatus for impregnating corrugated board including a serpentine fibrous intermediate layer, and a top and bottom planar fibrous outer layer having a predetermined height therebetween and cooperating with the serpentine layer to define a succession of transversely extending open-ended flutes having said predetermined height, comprising a. means for longitudinally feeding said board with said flutes and said planar outer layers being arranged horizontally and with said flutes extending normal to the longitudinal direction of feed; b. stationary impregnant supply means arranged adjacent one longitudinal edge of said longitudinally travelling board for supplying to one end of the flutes adjacent thereto an impregnating material, said impregnant supply means including
 2. said nozzle means being provided with a bore hole and an exit aperture having a cross-section taken in a vertical plane through the bore hole which is substantially triangular when viewed perpendicular to the cross section, and a cross-section taken in a horizontal plane through the bore hole which is substantially semicircular when viewed perpendicular to the cross section; c. said nozzle means and longitudinally feeding means being positioned such that said one longitudinal edge is positioned away from said nozzle means for allowing a gaseous medium entry to the flutes adjacent said nozzle means and concentrated jet as said concentrated jet is injected into said flutes for sheathing said jet as it enters said flutes, and d. stationary suction means disposed adjacent the other longitudinal edge of said board opposite said impregnant supply means for establishing a vacuum in said flutes to draw the impregnating material in said jet and said surrounding gaseous medium therethrough.
 3. Apparatus for impregnating corrugated board including a serpentine fibrous intermediate layer, and a top and bottom planar fibrous outer layer having a predetermined height therebetween and cooperating with the serpentine layer to define a succession of transversely extending open-ended flutes having said predetermined height, comprising a. means for longitudinally feeding said board with said flutes and said planar outer layers being arranged horizontally and with said flutes extending normal to the longitudinal direction of feed; b. stationary impregnant supply means arranged adjacent one longitudinal edge of said longitudinally travelling board for supplying to one end of the flutes adjacent thereto an impregnating material, said impregnant supply means including 